Wear resistant turbine fan blade

ABSTRACT

The disclosure generally relates to a wear resistant turbine fan blade having a composite lubricated sheet adhered to a root of the turbine fan blade and having improved tribological properties at high temperatures.

FIELD OF THE INVENTION

The disclosure generally relates to wear resistant turbine fan blades;more particularly to wear resistant turbine fan blades having acomposite lubricating sheet adhered to a root of the turbine fan blade.

BACKGROUND OF THE INVENTION

Typically, a wear resistant turbine fan blade is used to prevent or toreduce friction and wear when in sustained contact with other objectsdue to relative motion of both under high load and/or frictional forces.

SUMMARY OF THE INVENTION

A first aspect of the present invention relates to a wear resistantturbine fan blade comprising: a composite lubricating sheet adhered to aroot of the turbine fan blade, wherein the composite lubricating sheetcomprises: a fabric at least partially embedded with a resin, the fabricincluding an aromatic polyamide yarn, and a mixed yarn having thearomatic polyamide yarn and a low-friction yarn; and a metallic layeradhered to one side of the fabric.

A second aspect of the present invention relates to a turbine engineincluding at least one turbine fan blade having a composite lubricatingsheet adhered to a root of the turbine fan blade, wherein the compositelubricating sheet comprises: a fabric at least partially embedded by aresin, the fabric including an aromatic polyamide yarn and a mixed yarnhaving the aromatic polyamide yarn and a low-friction yarn; and ametallic layer adhered to one side of the resin embedded fabric.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will be more readilyunderstood from the following detailed description of the variousaspects of the invention taken in conjunction with the accompanyingdrawings that depict various embodiments of the invention, in which:

FIG. 1 depicts an embodiment of a wear resistant turbine fan blade, inaccordance with the present disclosure.

FIG. 2 depicts an embodiment of a wear resistant turbine fan blade inuse with a rotor disk.

It is noted that the drawings of the invention are not to scale. Thedrawings are intended to depict only typical aspects of the invention,and therefore should not be considered as limiting the scope of theinvention. In the drawings, like numbering represents like elementsbetween drawings.

DETAILED DESCRIPTION OF THE INVENTION

Fan blades used in the aerospace industry, and in particular, in turbineengines are often subjected to high pressure loads and high frictionalforces between the fan blades and other objects in contact with the fanblades resulting in surface wear and crack formation due to fatiguestress of the fan blades and/or objects in turbine engines. Improvementsin the wear resistance of fan blades is sought so as to improve thelifespan of the fan blades and/or objects in contact with the fanblades; to reduce the maintenance time of turbine engines; and toincrease the operational time of a device, assembly, airplane, etc. thatincorporate such fan blades. Wear means the deterioration of anyproperties of a solid surface by the action of another surface. Thedeteriorated properties may include, but are not limited to, thickness,smoothness, hardness, strength, and/or integrity. It has been discoveredthat the wear resistance of a fan blade may be improved or increased byhaving a composite lubricating sheet adhered to a root of the fan bladewhere the composite lubricating sheet has a metallic layer.

An embodiment of a wear resistant turbine fan blade is shown in FIG. 1,in accordance with the present disclosure. Referring to FIG. 1, a wearresistant turbine fan blade 2 is shown having composite lubricatingsheets (CLS) 8 adhered thereon. In particular, the CLSs 8 are adhered toa root 9 of turbine fan blade 2. Reference 5 connotes that turbine fanblade 2 may continue beyond reference 5 to form a larger, completeturbine fan blade. Turbine fan blade 2 may be an integrated component ina turbine engine, a rotor disk, and a rotor disk assembly. Turbine fanblade 2 may comprise a metal selected from titanium, aluminum, steel,nickel, and alloys thereof. In an embodiment, turbine fan blade 2 maycomprise titanium. In another embodiment, turbine fan blade 2 maycomprise steel. In another embodiment, turbine fan blade may comprisealuminum.

CLS 8 may comprise a fabric 6 and a metallic layer 7 adhered to one sideof fabric 6. Fabric 6 may be at least partially embedded with a resin,and may include an aromatic polyamide yarn and a mixed yarn having thearomatic polyamide yarn and a low-friction yarn. The aromatic polyamideyarn may be a plurality of fibers in a bundle, including fibercomprising an aromatic polyamide, used for weaving. The aromaticpolyamide yarn may include yarns made from but not limited topoly(para-phenylene terephthalamide), poly(meta-phenyleneterephthalamide), poly(meta-phenylene isophthalamide),poly(para-phenylene isophthalamide), combinations thereof, andcopolymers thereof.

The low-friction yarn may be a yarn having a coefficient of friction(COF) against itself which is lower than the COF of the aromaticpolyamide yarn against itself. The low-friction yarn may comprisegraphite or a fluoropolymer. In an embodiment, the low-friction yarn maycomprise graphite fiber or a fluoropolymer fiber. In an embodiment, thefluoropolymer fiber may be polytetrafluoroethylene fiber. Resin embeddedfabric 6 may be at least partially embedded with a resin selected from,but not limited to, a phenolic resin, an epoxy resin, or a polyimideresin. In an embodiment, the phenolic resin may comprisephenol-formaldehyde.

Metallic layer 7 may comprise a metal selected from titanium, aluminum,steel, and nickel. In an embodiment, metallic layer 7 may be titanium.In another embodiment, metallic layer 7 may be steel. Metallic layer 7may have a thickness in a range from approximately 20 microns toapproximately 1,000 microns. In an embodiment, metallic layer 7 may havea thickness in a range from approximately 50 microns to approximately250 microns. In another embodiment, metallic layer 7 may have athickness in a range from approximately 70 microns to approximately 100microns. In another embodiment, metallic layer 7 may have a thickness ofapproximately 90 microns.

Metallic layer 7 may be in the form a metallic foil. In an embodiment,the metallic foil may be a thin, flexible sheet of titanium, aluminum,steel, or nickel. In an embodiment, metallic layer 7 may be a titaniumfoil. In another embodiment, the metallic foil may have a thickness in arange from approximately 20 microns to approximately 1,000 microns. Inanother embodiment, the metallic foil may have a thickness in a rangefrom approximately 50 microns to approximately 250 microns. In anotherembodiment, the metallic foil may have a thickness in a range fromapproximately 70 microns to approximately 100 microns. In anotherembodiment, the metallic foil may have a thickness of approximately 90microns. Metallic layer 7 may be adhered to one side of resin embeddedfabric 6.

In an embodiment, metallic layer 7 may be a pure metal comprising asingle metallic element. In another embodiment, metallic layer 7 may bea metal alloy comprising two or more metallic elements. When two or moremetallic elements are a part of metallic layer 7, any element may be amajor or predominant element by weight percent. Embodiments of elementspresent in metallic layer 7 include, but are not limited, to titanium,iron, aluminum, copper, nickel, zinc, tungsten, molybdenum, tin, andcobalt. Any of the aforementioned elements may be the major orpredominant element by weight percent.

Metallic layer 7 may have a Vickers hardness value HV of approximately30 or greater at a load of 100 g applied for 20 seconds according toASTM E-384. In an embodiment, metallic layer 7 may have a Vickers HV ofapproximately 100 or greater. In another embodiment, metallic layer 7may have a Vickers HV of approximately 200 or greater. In anotherembodiment, metallic layer 7 may have a Vickers HV of approximately 300or greater.

An example of composite lubricating sheet 8 having a titanium metalliclayer 7 is Vespel® ASB-0670 product grade available from E.I. du Pont deNemours and Company. Other Vespel® composite lubricating sheet 8 productgrades may include metallic layer 7 being steel, aluminum, or nickel.

Composite lubricating sheet (CLS) 8 may have a thickness in a range from30 microns to 3 mm. In embodiment, CLS 8 may have a thickness in a rangefrom 50 microns to 1 mm. In another embodiment, the thickness may be ina range from 100 microns to 750 microns.

CLS 8 may have a Compression Fraction value in a range from 0.1% (0.001)to approximately 20% (0.20) with a pressure applied by compressing atapproximately 127 microns/minute up to approximately 450 MPa and thenreleased. Compression Fraction means the fraction of thickness lost dueto compression under specific conditions. In an embodiment, compositelubricating sheet 8 may have a Compression Fraction value in a rangefrom 1% (0.010) to approximately 5.7% (0.057). In another embodiment,the Compression Fraction value may be in a range from 1.3% (0.013) toapproximately 3% (0.030). The aforementioned Compression Fraction valueembodiments may be determined with a pressure applied by compressing atapproximately 127 microns/minute up to approximately 450 MPa and thenreleased.

CLS 8 may be adhered to turbine fan blade root 9 to form wear resistantturbine fan blade 2. The adherence of CLS 8 may be achieved throughphysical or chemical bonding. One may also use an adhesive such asthermoplastic adhesive, a thermoset adhesive, and other bondingadhesives known in the art. In particular, metallic layer 7 may beadhered to blade root 9. In an embodiment, the thermoset adhesive may bean epoxy adhesive. The bonding adhesive layer may have a thickness inrange from approximately 2 microns to 2,000 microns. In an embodiment,the thickness may be in a range from approximately 10 microns to 100microns. In another embodiment, the thickness may be in a range fromapproximately 20 microns to 80 microns.

Prior to adhering CLS 8 to blade root 9, the surface of metallic layer 7to be adhered to blade root 9 and/or the surface of blade root 9 may besurface treated. Surface treatment may be performed by any known processin the art to treat a metallic surface. In an embodiment, surfacetreatment may be performed by a peening process. Typical peeningprocesses involve the impacting a surface with numerous, smallparticles. An example of a peening process is shot peening. Theshot-peened, roughened surface may have a characteristic roughnessidentifiable by the appearance of small craters in the surface. Inanother embodiment, surface treatment may include sandblasting thesurface of metallic layer 7 to be adhered to blade root 9 and/orsandblasting the surface of blade root 9. In another embodiment, surfacetreatment may include chemical etching of the surface of metallic layer7 to be adhered to blade root 9 and/or chemical etching the surface ofblade root 9. In another embodiment, surface treatment may include beltsanding of the surface of metallic layer 7 to be adhered to blade root 9and/or belt sanding the surface of blade root 9.

The aforementioned surface treatments may be performed in combination totreat the surface of metallic layer 7 and/or the surface of blade root9. For example, the surface of metallic layer 7 to be adhered to bladeroot 9 may be first shot-peened and then the shot peened surface may betreated by sandblasting prior to adhesion to blade root 9.

During normal use, the wear resistant turbine fan blade 2 disclosedherein may typically come in sustained contact and movement, throughresin embedded fabric 6 of composite lubricating sheet 8, with anotherobject(s) under a high pressure load and under vibratory, reciprocating,and/or circular motions. The high pressure load may be in a range fromapproximately 100 MPa to approximately 600 MPa. Wear resistant turbinefan blade 2 in sustained contact with another object may have aCoefficient of Friction (COF) value in a range from 0.01 to 0.1. In anembodiment, the COF value may be less than approximately 0.05. Inanother embodiment, the COF value may be less than 0.04.

The utility of wear resistant turbine fan blade 2 may be demonstrated bymeasuring the durability of CLS 8 under controlled pressure and wearconditions. Wear under pressure may be demonstrated, for example, by:providing a body having a surface subject to wear, such as a titaniumblock with a known roughness; adhering to the surface subject to wearcomposite lubricating sheet 8 wherein the adhering occurs between themetallic layer 7 and the titanium surface subject to wear; providing anobject having a wear surface such as another titanium block; aligningresin embedded fabric 6 of CLS 8 with the wear surface of the otherobject with a pressure in a range from approximately 210 MPa toapproximately 500 MPa; and causing resin embedded fabric 6 of CLS 8 tobe in sustained contact with the surface of the other object.

EXAMPLES

The present disclosure may be further defined by the following examples.It should be understood that the following examples, while indicatingembodiments of the present disclosure, are given by way of illustrationonly. From the above discussion and the following examples, one havingordinary skill in the art can ascertain the essential characteristics ofthe present disclosure, and without departing from the spirit and scopethereof, may make various changes and modifications of the presentdisclosure to adapt it to various uses and conditions.

Table 1 lists Vickers Hardness values (HV) for metallic layer 7 ofcomposite lubricating sheet (CLS) 8. Values listed in Table 1 are formetallic layer 7 in the form of a metallic foil. Vickers Hardness valuesare described in ASTM E-384 which is incorporated herein by reference inits entirety. Unless otherwise specified, HV in Table 1. means HV 0.1/20as determined with 100 gram force applied for 20 seconds.

TABLE 1 Designation Foil-1 Foil-2 Foil-3 Foil-4 Foil 5 Foil-6 MaterialFe Ti Ti Ti Al Al Foil Stainless ASTM ASTM Descrip- Steel, B265, B265,tion Type 304 Grade = Grade = 4 9 Thickness 75 70 90 460 125 125 (microns) Meltallic layer Hardness, 407 252 224 176 39.1 23* HV 0.1/20HV Std Dev 13 10 2.5 6.4 0.3   0.8 *Foil-6 Hardness HV is determinedwith 50 g for 20 seconds (HV 0.05/20)

CLS 8 of the present disclosure may be resistant to crushing bycompressive forces. In one embodiment, a suitable test for resistance tocompressible forces is to determine the fraction of compression that astrong compressive force produces. Table 2 lists Compression Fractionpercentage values for CLS 8 having various metallic layers 7 and anentry (10) for CLS 8 without a metallic layer for comparison.

TABLE 2 CLS 1 2 3 4 5 6 C1 Metallic Fe Ti Ti Ti Al Al None LayerThickness, 370 370 400 800 460 435 280 microns Compression 2.6 1.6 2.81.42 5.83 6.55 8.63 Fraction, %

In Table 2, CLS test samples 2, 3, and 4 are representative samples ofVespel ASB-0670 product grade available from E.I. du Pont de Nemours andCompany in which the metallic layer is titanium. CLS test samples 1, 5,and 6 are representative samples of other Vespel® composite lubricatingsheet 8 product grades in which the metallic layer 7 is steel (Fe) andaluminum. CLS test sample C1 is a comparative sample in which it doesnot have a metallic layer 7.

Compression fraction percentage values of CLSs 8 were determined using aMitutoyo IP 54 micrometer and an Instron 1332 fatigue system with n 8800controller. The Mitutoyo IP 54 micrometer was used to measure thicknessof CLS by first measuring the initial thickness of a CLS square ofapproximately 25 mm by approximately 25 mm. The Instron 1332 fatiguesystem was used to apply compressive loads to the CLS square. Themeasured CLS square was then compressed with a 10 mm by 10 mmshot-peened surfaced Ti block to 450 MPa applied at 0.05 inch/min (1270microns/min) using the Instron 1332 fatigue system. When 450 MPapressure was achieved, the pressure was released and measurement of thefinal thickness of the CLS square was made within one minute using theMitutoyo IP 54 micrometer.

CLS 8 of the present disclosure may be resistant to crushing bycompressive forces and wear through rubbing/frictional forces. In oneembodiment, a suitable test for resistance to compressible forces andsimultaneous frictional force is to determine the Minimum Strokes numberCLS 8 may sustain before succumbing to failure. Table 3 lists MinimumStrokes values for CLS 8 having a titanium metallic layer 7 and for CLS8 without a metallic layer for comparison.

TABLE 3 CLS 1* 2* 3 Metallic Layer Ti Ti None Pressure, MPa 400 400 400Minimum Strokes 43,527 44,244 362 *Two sets of test specimens used.

In Table 3, CLS test samples 1 and 2 are representative samples ofVespel® ASB-0670 product grade available from E.I. du Pont de Nemoursand Company in which the metallic layer is titanium. CLS test sample C1is a comparative sample in which it does not have a metallic layer 7.

Minimum Strokes values of CLSs 8 in use with a metal substrate weredetermined using an Instron 1321 fatigue system with an 8800 controller.The Minimum Strokes values were reported as the number of reciprocatingtest strokes of 1.2 mm in length applied at 10 Hz accomplished by therelative motion of the article with respect to resin embedded fabriclayer 6 of CLS 8.

Prior to evaluating wear under pressure, the resin embedded fabric layer6 of CLS 8 was lightly coated with a lubricant containing afluorochemical by spraying or painting the lubricant on the surface ofthe resin embedded fabric layer 6. The spraying or coating provides athin translucent to an opaque coating of lubricant.

CLS 8 was adhered to a stationary metal substrate by an epoxy adhesivesuch as for example, NB 101 available from Newport Adhesives andComposites, Inc; Irvine, Calif. The stationary metal substrate was asandblasted, 20 mm by 20 mm titanium block with a peen-hardened surfacehaving a Rockwell C33 hardness. The metallic layer of CLS 8 was adheredto the titanium block with resin embedded fabric layer 6 of CLS 8 facingaway from the titanium block. The adhesive was oven cured under lowpressure (approximately 5 psi) comprising a first heating step toapproximately 79° C. for 90 min and then a second heating step toapproximately 149° C. for an hour. The titanium block was then mountedin the lower carrier of the Instron 1321 with CLS 8 facing up.

A second titanium block with a peen-hardened surface (Rockwll C33hardness) measuring approximately 10 mm by 10 mm and microns was mountedin an upper carrier of the Instron 1321 and brought into parallelreversible contact with CLS 8 aligned in the center of the titaniumblock in the lower carrier. The pressure between the blocks was raisedto 400 MPa, and reciprocating strokes were applied at a rate of 10forward and 10 backward strokes per second with a stroke length of 1.2mm. Testing was run until the onset of failure, i.e., a corner of the 10mm by 10 mm titanium block penetrated resin embedded fabric layer 6 ofCLS 8. The Minimum Strokes value represents the number of strokes toreach test specimen failure. The larger the Minimum Strokes value, thebetter the performance of CLS 8.

Comparing CLS test samples 1 and 2 having a titanium metallic layer(Vespel® ASB-0670 product grade) to comparative test sample C1 nothaving a metallic layer, an approximate 100 fold improvement in wearresistance was achieved for test samples 1 and 2. Under test conditions,a value greater than 10,000 Minimum Strokes represents durability tolast through, for example, an engine maintenance cycle.

Another embodiment of a wear resistant turbine fan blade is shown inFIG. 2, in accordance with the present invention. Referring to FIGS. 1and 2, a wear resistant turbine fan blade 2 is shown having compositelubricating sheets (CLS) 8 adhered on turbine fan blade root 9. Turbinefan blade 2 may be an integrated component in a turbine engine.Embodiments of turbine fan blade 2 and CLS 8 have been previouslydescribed and are herein incorporated by reference in their entirety.

CLSs 8 may protect fan blade root 9 from deterioration when in use with,for example, a rotor disk 26. The forces and loads experienced betweenfan blade root 9 and rotor disk 26 during operation of a turbine engineare known in the art. Performance characteristics of compositelubricating sheet 8 have been previously described and are hereinincorporated by reference in their entirety. The performance testsconducted are representative of the forces and loads experienced betweenfan blade root 9 and rotor disk 26 during operation of a turbine engine.In another embodiment, CLS 8 may be adhered to a metal substrate such asa shim, metallic layer, or any part already adhered to fan blade root 9.The shim, metallic layer, etc. may comprise a metal selected fromtitanium or steel.

An embodiment of a turbine engine is described, in accordance with thepresent invention. The turbine engine may include at one turbine fanblade having a composite lubricated sheet adhered thereon. Embodimentsand performance characteristics of the composite lubricating sheet havebeen previously described and are herein incorporated by reference intheir entirety. Embodiments of the turbine fan blade having a compositelubricating sheet adhered therein have been previously described.

The terms “first”, “second”, and the like, herein do not denote anyorder, quantity, or importance, but rather are used to distinguish oneelement from another, and the terms “a” and “an” herein do not denote alimitation of quantity, but rather denotes the presence of at least oneof the referenced items. The modifier “about” used in connection with aquantity is inclusive of the state value and has the meaning dictated bythe context, (e.g., includes the degree of error associated withmeasurement of the particular quantity). The suffix “(s)” as used hereinis intended to include both the singular and the plural of the term thatit modifies, thereby including one or more of that term (e.g., themetal(s) includes one or more metals). Ranges disclosed herein areinclusive and independently combinable (e.g., ranges of “toapproximately 25 wt %, or, more specifically, approximately 5 wt % toapproximately 20 wt %”, is inclusive of the endpoints and allintermediate values of ranges of “approximately 5 wt % to approximately25 wt %”, etc.)

While various embodiments are described herein, it will be appreciatedfrom the specification that various embodiments of elements, variationsor improvements therein may be made by those skilled in the art, and arewithin the scope of the invention. In addition, many modifications maybe made to adapt a particular situation or material to the teachings ofthe invention without departing from essential scope thereof. Therefore,it is intended that the invention not be limited to the particularembodiment disclosed as the best mode contemplated for carrying out thisinvention, but that the invention will include all embodiments fallingwithin the scope of the appended claims.

What is claimed is:
 1. A wear resistant turbine fan blade comprising: acomposite lubricating sheet adhered to a root of the turbine fan blade,wherein the composite lubricating sheet comprises: a fabric at leastpartially embedded with a resin, the fabric including an aromaticpolyamide yarn, and a mixed yarn having the aromatic polyamide yarn anda low-friction yarn; and a metallic layer adhered to one side of thefabric.
 2. The turbine fan blade according to claim 1, wherein theturbine fan blade is an integrated component of a machine selected fromthe group consisting of a rotor disk, a rotor assembly, and a turbineengine.
 3. The turbine fan blade according to claim 2, wherein theturbine fan blade is an integrated component of a turbine engine.
 4. Theturbine fan blade according to claim 1, wherein the turbine fan bladecomprises a metal selected from the group consisting of titanium,aluminum, steel, nickel, and alloys thereof.
 5. The turbine fan bladeaccording to claim 4, wherein the turbine fan blade is titanium.
 6. Theturbine fan blade according to claim 1, wherein the resin isphenol-formaldehyde resin.
 7. The turbine fan blade according to claim1, wherein the aromatic polyamide yarn is selected from the groupconsisting of poly(para-phenylene terephthalamide), poly(meta-phenyleneterephthalamide), poly(meta-phenylene isophthalamide),poly(para-phenylene isophthalamide), combinations thereof, andcopolymers thereof.
 8. The turbine fan blade according to claim 1,wherein the low-friction yarn comprises graphite fiber or afluoropolymer fiber.
 9. The turbine fan blade according to claim 8,wherein the fluoropolymer fiber comprises a polytetrafluoroethylene. 10.The turbine fan blade according to claim 1, wherein the metallic layeris a metal selected from the group consisting of titanium, aluminum,steel, and nickel.
 11. The turbine fan blade according to claim 10,wherein the metallic layer is titanium.
 12. The turbine fan according toclaim 1, wherein the metallic layer has a thickness in a range fromapproximately 50 microns to approximately
 250. 13. The turbine fan bladeaccording to claim 1, wherein the metallic layer has a Vickers Hardnessof approximately 30 HV or greater at a load of approximately 100 gramsapplied for approximately 20 seconds according to ASTM E-384.
 14. Theturbine fan blade according to claim 1, wherein the compositelubricating sheet has a Compression Fraction in a range of 0.1% toapproximately 20% with a pressure applied by compressing atapproximately 127 microns/minute up to approximately 450 MPa and thenreleased.
 15. The turbine fan blade according to claim 1, wherein thecomposite lubricating sheet additionally comprises an attaching layerbetween the fabric and the metallic layer, attaching layer comprising anadhesive selected from the group consisting of a thermoplastic adhesiveor a thermoset adhesive.
 16. A turbine engine including at least oneturbine fan blade having a composite lubricating sheet adhered to a rootof the turbine fan blade, wherein the composite lubricating sheetcomprises: a fabric at least partially embedded by a resin, the fabricincluding an aromatic polyamide yarn and a mixed yarn having thearomatic polyamide yarn and a low-friction yarn; and a metallic layeradhered to one side of the resin embedded fabric.
 17. The turbine engineaccording to claim 16, wherein the the aromatic polyamide yarn isselected from the group consisting consisting of poly(para-phenyleneterephthalamide), poly(meta-phenylene terephthalamide),poly(meta-phenylene isophthalamide), poly(para-phenyleneisophthalamide), combinations thereof, and copolymers thereof; and thelow-friction yarn comprises graphite or a fluoropolymer.
 18. The turbineengine according to claim 16, wherein the metallic layer is a metalselected from the group consisting of titanium, aluminum, steel, andnickel.
 19. The turbine engine according to claim 16, wherein themetallic layer has a Vickers Hardness of approximately 30 HV or greaterat a load of approximately 100 grams applied for approximately 20seconds according to ASTM E-384.
 20. The turbine engine according toclaim 16, wherein the composite lubricating sheet has a CompressionFraction in a range of 0.1% to approximately 20% with a pressure appliedby compressing at approximately 127 microns/minute up to approximately450 MPa and then released.